Ribnik is a fortified town southwest of Ozalj, in the Obvrh Creek Valley. In the 13th–14th centuries the estate was the property of the Baboni? family and Ban Mikac. In 1394, it was acquired by the Frankopans, who built the town we see today. Ribnik is surrounded by a moat crossed by a drawbridge. The fortress has two floors and is partly built of well-cut stone. It is in the shape of an irregular circle, with an arcaded courtyard at the centre. The defence tower (near the main entrance) bearing the Frankopan coat of arms was very high; opposite it was a pentagonal tower. Between the two towers there were several buildings arranged in the form of a ring. A number of Gothic and Renaissance architectural details are still intact.